This invention relates to a steering column assembly.
U.S. Patent Application Publication 2003/0 155 760 A1 discloses a steering column assembly that has a steering column which is secured via a bracket carriage to a bracket fixed to the vehicle. The bracket carriage is displaceably mounted on the bracket and is secured to the bracket by attachment means in such a way that the bracket carriage and bracket cannot be displaced in relation to one another when used in the intended fashion. If a force applied to the steering column assembly by a vehicle occupant exceeds a certain force, for example in the event of a crash, the attachment means become detached so that the bracket carriage is displaced in relation to the bracket. The steering column is displaced with the bracket carriage so that additional space is provided for the vehicle occupant. It is conceivable to provide a crash element which absorbs the defined amount of energy during the displacement of the bracket carriage in relation to the bracket.
The attachment means which are known from this document and which have the purpose of securing the bracket carriage to the bracket are composed of a plurality of elements. For example, a screw is provided which plugs through the bracket carriage and is screwed into the bracket which is fixed to the vehicle. Mechanical elements with different functions such as a nut, a spring, various washers, sleeves and recess elements are arranged around the screw. The attachment means carry out the task of securing the bracket carriage with respect to the bracket when, as already described above, the steering column assembly is used in the intended fashion. If a force which is applied to the steering column assembly exceeds a specific amount, the attachment means release the bracket carriage so that the latter can be displaced in relation to the bracket.
The present invention is based on the object of providing a steering assembly which can be reliably collapsed in the event of an accident and is simple and cost-effective to manufacture.
This object is achieved according to the invention by means of a steering column assembly having the features claimed.
Accordingly, the invention is distinguished by the fact that a steering column assembly having a steering column is mounted by means of a bracket carriage on a bracket which is arranged fixed to the vehicle, the bracket carriage being arranged so as to be displaceable relative to the bracket. In order to bring about freedom from play between the bracket carriage and bracket during use in the intended fashion, attachment means are provided for securing the bracket carriage to the bracket. According to the invention, these attachment means are integrally formed in one piece either to the bracket or the bracket carriage or to both components. In other words, the bracket and/or bracket carriage are configured or manufactured as mechanical components in such a way that they have elements which permit one component to be secured to the other component without the aid of additional attachment means. Configuring the attachment means in one piece provides the advantage of being able to reduce costs which would be incurred in manufacturing and mounting additional separate attachment elements. Since the attachment elements are dispensed with by integrating the attachment function into the bracket carriage and bracket components, these costs can be eliminated, which provides a considerable potential for savings, in particular in the case of a series-manufactured product such as a steering column.
According to one embodiment, the attachment means can produce a detachable connection between the bracket and bracket carriage. This provides the advantage that the connection between the bracket carriage and bracket can be released at a specific time so that relative movement between the bracket carriage and bracket is made possible. This may occur, for example, in the case of a crash in which a force which exceeds a predetermined amount is applied to the steering column assembly. The attachment means can then be configured in such a way that they do not release the connection between the bracket and bracket carriage until the force which is applied from the outside exceeds the specific amount.
It is conceivable for the attachment means to be configured as face pairings that interact with one another. Furthermore, it is possible to produce a certain degree of stress between the components, depending on which position the components assume with respect to one another. In particular, stress can be built up between the two components if one of the components becomes deformed during the mounting process. Prestress which connects the two components to one another is brought about through such deformation. The components which are to be connected to one another can be moved in relation to one another, for example, until a predetermined force level is developed, at least one of the components being deformed during this movement. The particular advantage of such a connection is to be seen in the fact that very secure anchoring with simultaneous rigidity of the module can be brought about.
The attachment means can be composed of interacting faces which have angles which are matched to one another. During the mounting process, it is thus possible to predefine a specific direction which the components assume if they are displaced with respect to one another during the mounting process. If a stay is also provided, a tension or a surface pressure between the two components can easily be established by means of the interacting faces and this stay. It is also conceivable for one component to have oblique faces and the other to be deformed by interacting with the oblique faces during mounting.
In order to set the surface pressure it is conceivable to match the materials of the faces and of the deforming components precisely to one another. This is possible, for example, by manufacturing the entire components from corresponding materials. It is likewise conceivable for the surfaces of the interacting faces to be coated with corresponding materials. Selective configuration of the surfaces of the faces which interact with one another in order to set a defined surface pressure is also conceivable.
So that the connection between the steering column and bracket is maintained if the bracket carriage is displaced relative to the bracket, the bracket carriage can have a holder which is mounted in such a way that at the end of the movement of the bracket carriage in relation to the bracket it brings about a secure connection between the steering column and bracket by means of the bracket carriage. The holder can be embodied in at shape and can be manufactured as a sheet metal clip from the same material as the carriage. A guide which is adapted to the sheet metal clip and which is configured in such a way that reliable connection between the bracket and bracket carriage is ensured can be provided in the bracket. The sheet metal clip in the bracket carriage is an easy-to-manufacture connecting element if the bracket carriage is also made of sheet metal. In order to manufacture the sheet metal clip all that has to be done is to merely adapt the shape of the tool correspondingly. The same applies to the guiding in the bracket. If the bracket is manufactured by means of an injection molding method, the mold simply has to be correspondingly adapted. There are no additional work steps which would have to be carried out during the manufacture.
It is conceivable to secure the bracket carriage to the bracket by means of additional tear off pins. Tear off pins provide the advantage that the tear off force or the force of the crash, that is to say the force above which the bracket carriage moves relative to the bracket, can easily be set in a precise fashion. In addition, tear off pins are components which are easy to manufacture and easy to mount. It is conceivable to build up part of the force of the crash by means of the prestress which is set between the components. The remaining proportion can be generated by means of the tear off pins. The system both reduces the number of components and has the advantage that it can be adjusted satisfactorily.
The invention will be explained in more detail below with reference to the exemplary embodiment illustrated in the drawings.